Fuse holder including coordinated operating means between fuse insertion and an associated circuit breaker device



F. E. MYERS 3,474,373 uss HOLDER INCLUDING COQHDINATED OPERATING mums BETWEEN FUSE mssa'rzou AND AN ASSOCIATED CIRCUIT BREAKER DEVICE' a Filed June 22, 1967 5 Sheets-Sheet 1 IN VEN TOR. F51 A! Z/VYf/Kf Oct. 21, 1969 MYERS FUSE HOLDER INCLUDING COORDINATED OPERATING MEANS BETWEEN FUSE INSERTION AND AN ASSOCIATED CIRCUIT BREAKER DEVICE Filed June 22, 1967 5 Sheets-Sheet 2:

Oct. 21, 1969 F. E. MYERS 3,474,373 FUSE HOLDER INCLUDING COORDINATED OPERATING MEANS BETWEEN FUSE INSERTION AND AN ASSOCIATED CIRCUIT BREAKER DEVICE Filed June 22, 1967 5 Sheets-Sheet 3 Oct 21. 1969 F. E. MYERS FUSE HOLDER INCLUDING COORDINATBD OPERATING MEANS BETWEEN FUSE INSERTION AND AN ASSOCIATED CIRCUIT BREAKER DEVICE Filed June 22, 1967 5 Sheets-Sheet 4 Oct. 21, 1969 MYERS 3,474,373

FUSE HOLDER INCLUDING COORDINATED OPERATING MEANS BETWEEN I FUSE INSERTION AND AN ASSOCIATED CIRCUIT BREAKER DEVICE Filed June 22, 1967 I Sheet 5 5 Sheets- I IS.

M MM United States Patent FUSE HOLDER INCLUDING COORDINATED OPERATING MEANS BETWEEN FUSE IN- SERTION AND AN ASSOCIATED CIRCUIT BREAKER DEVICE Felix E. Meyers, Cherry Hill, N.J., assignor, by mesne assignments, to I-T-E Imperial Corporation, Philadelphia, Pa., a corporation of Delaware Filed June 22, 1967, Ser. No. 648,062

Int. Cl. H01h 71/20, 73/22 US. Cl. 337-154 13 Claims ABSTRACT OF THE DISCLOSURE In a device for removably receiving a fuse in conjunction with a circuit breaker, an interlock means is provided to prevent insertion of the fuse while the breaker contacts are on, and to automatically trip the breaker open upon fuse removal. The fuse is held by a fuse holder, which includes means for insuring proper insertion of the fuse within the fuse compartment, and serves to retain the properly installed fuse within the fuse compartment.

My invention relates to the use of an interlock arrangement for coordinating a current limiting fuse to its associated circuit breaker device, to insure that the circuit breaker contacts are disengaged prior to removal of a fuse, and during the insertion of a new fuse. Further, the fuse holder includes a protrusion means, which registers with complementary recesses of the fuse compartment to insure proper coordination between-the interlock means and retain the properly inserted fuse within its compartment.

In copending US. patent application, entitled Circuit Protection Arrangement Including Coordinated Operation of a Circuit Breaker and a Current Limiting Fuse, Ser. No. 647,999, filed on even date herewith in the name of Carl E. Gryctko and assigned to the assignee of the instant invention, there is disclosed a compact assembly of a circuit breaker and current limiting fuse. The assembly is intended to removably receive a current limiting fuse, which when properly inserted and the circuit breaker contacts closed, is series connected to the circuit breaker to provide coordinated protection of the particular circuit. In order to insure proper safety of operation, it is imperative that the insertion of the fuse can only take place when the circuit breaker cont-acts are disengaged, and hence the fuse terminals will be dc-energized. Conversely, when it is desired to remove the fuse from its fuse compartment, the circuit breaker should be automatically tripped open, in order to prevent access to energized fuse terminals.

My invention accomplishes these objectives in an extremely reliable and simplified manner, by the provision of a novel interlock and fuse holder structure, for coordinating fuse removal with the circuit breaker operations. The circuit breaker is illustratively shown as a well known commercial type, generally in accordance with the structure shown in U.S. Patent No. 2,996,589, issued Aug. 15, 1961, in the name of F. E. Myers, entitled Pivoted Bimetal and assigned to the assignee of the instant invention. Such a circuit breaker device includes the latched engagement of a spring-biased cradle member and a latch member. The latch member is secured to the free end of an elongated bimetal, which is conventionally moved to the trip position by either deflective movement of the bimetal, or actuation of an associated armature member. In accordance with my invention, I also provide an interlock lever, having a first end in close proximity to the bimetal free end, and a second end extending into the fuse compartment. The interlock lever is biased into engagement, with the free end of the elongated bimetal in a direction to effect unlatching of the cradle, and hence tripping of the circuit breaker. This movement is, however, restrained at the opposite end of the interlock lever by its engagement with the fuse holder. More specifically, the fuse holder, which is rotatably inserted within the fuse compartment, includes a cam surface, which controls the movement of the interlock lever.

The fuse holder cam surface is so designed that upon complete insertion of the fuse within its compartment, the interlock lever tripping end is prevented from moving into engagement with the elongated bimetal. However, as the fuse holder is rotated for fuse removal, its cam surface permits the biased movement of the interlock lever in a direction to bring about tripping of the breaker. In order to insure proper operation of the interlock lever, the fuse holder includes circumferentially spaced protrusions, which register with cooperating recesses of the fuse compartment, during fuse insertion and fuse removal.

The protrusions are located in conjunction with the cooperating fuse compartment recesses, to insure that the fuse may only be inserted within its fuse compartment when the interlock lever is moved to the tripping position. Further, these protrusions and cooperating fuse compartment recesses guide the rotation of the fuse holder to the fully inserted position, and prevent fuse removal in this position. That is, the fuse holder must be rotated back (to the condition that causes interlock tripping) prior to removal of the fuse.

It is therefore seen that my invention provides a reliable interlock arrangement for coordinating the removal and insertion of a current limiting fuse, with the tripping action of its associated circuit breaker device.

It is, therefore, a primary object of my invention to provide a coordinated circuit :breaker and current limiting fuse, which includes an interconnecting safety interlock.

A further object of my invention is to provide such a safety interlock, which insures tripping of the circuit breaker before removal of the current limiting fuse.

Another object of my invention is to provide such a safety interlock, which also insures that the circuit breaker is in its tripped open condition during the insertion of a fuse.

An additional object of my invention is to provide a safety interlock connection between a current limiting fuse compartment and circuit breaker device, which includes a novel interlocking lever between the circuit breaker trip latch and the current limiting fuse holder.

Still another object of my invention is to provide such a safety interlock arrangement, wherein the fuse holder includes a circumferential cam surface, for controlling the movement of the interconnecting interlock lever.

Still a further object of my invention is to provide such a safety interlock arrangement, in which the fuse holder includes protrusion means, cooperatively associated with registry means of the fuse compartment for governing the manner of fuse insertion, and retaining the properly inserted fuse Within the compartment.

These as well as other objects will become readily apparent upon consideration of the following description and drawings, in which:

FIG. 1 is a simplified perspective view showing the unitized circuit breaker and current limiting fuse device, utilizing the instant invention, and depicting the manner in which the fuse may be readily inserted within its compartment.

-FIG. 2 is a front view, with the cover removed and the fuse fully inserted, showing the manner in which the camming engagement of the interlock lever and fuse holder prevents tripping operation of the interlock lever.

FIG. 3 is a detailed view, showing the manner in which the current limiting fuse in its fuse holder may be readily inserted within the fuse receiving compartment.

FIG. 4 is a top view, taken along the line 4--4 of FIG. 2, with the cover replaced.

FIG. 5 is a side view taken in the direction of line 5-5 of FIG. 2.

FIG. 6 is a simplified representation of FIG. 2, and showing the manner in which the removal of the fuse starts to bring the circuit breaker device towards its tripping condition.

FIGS. 7 and '8 sequentially follow FIG. 6 and show the manner in which actual tripping of the circuit beraker is effected during the removal operation of the current limiting fuse.

FIGS. 9, 10 and 11 are elevation, top and cross-sectional views respectively of the fuse holder.

FIGS. 12 and 13 are elevation and top views respectively of the interlock lever.

FIG. 14 is a cross-sectional view along the line 14-14 of FIG. 2, and showing the manner in which one of the fuse holder protrusions is located within its complementary fuse compartment annular guide recess.

FIG. 15 is a cross-sectional view along the line 15--15 of FIG. 2, and showing the manner in which the other fuse holder protrusion is located within its complementary fuse compartment annular guide recess.

Referring initially to FIGS. 1-5, the novel interlock arrangement of the subject invention is illustratively shown in conjunction with a single phase embodiment of the unitized circuit breaker and current limiting protective device 20, which is the subject of aforementioned US. patent application Ser. No. 647,999. It should, however, be understood that the inventive concepts residing in the interlock structure of my invention may be utilized in conjunction with other circuit breaker devices, wherein it is desired that the insertion and removal of the current limiting fuse be properly coordinated, with the tripping of the circuit breaker.

Unitized device includes a molded housing, having a base section 22, and a complementary cover section 24, held together by a plurality of rivets 26. The housing includes a pair of opposed first and second side walls 34, 36, respectively; and a pair of opposed front and rear walls 38, 40, respectively. The internal volume bounded by the above-noted walls 30, 32, 34, 36, 38 and 40 is separated into two compartments by a dividing region, generally shown by the dotted line 42. The first compartment44 includes a circuit breaker device, generally constructed in accordance with the general teachings of aforementioned U.S. Patent No. 2,996,589. The longitudinally adjacent second compartment 46 contains the current limiting fuse 50, which is appropriately circuit connected to the circuit breaker device, in a manner which will henceforth be described, so as to provide a series circuit connection therebetween.

Unitized device 20 includes an external line terminal 100, which is connected to an external source of electrical energy (not shown) in the conventional manner. Load terminal 110 is provided at the opposite side of the circuit breaker device 20 for connection to an external load (not shown). The circuit breaker device within compartment 44 is advantageously of a type which has achieved wide-scale utilization for home and light industrial use, and has advanced to the point where it is extremely reliable and efficient in operation, and may be rapidly and economically manufactured.

Compartment 44 includes a plurality of recesses for receiving and locating the various operating components of the circuit breaker. Located within these recesses is a stationary contact 102, which is connected to line terminal 100, via conductive member 101. Cooperating with stationary contact 102 is a movable contact 104, mounted to the lower end of a bifurcated contact arm 106. Parallel plate arc extinguishing means 108 is provided within recesses 109. The upper bifurcated end of contact arm 106 abuts a suitable pivot formation'of internally extending portion 112 of manual operating member 114. Manual operating member 114 is pivoted about a housing protrusion 113, which is entered into suitable aligned recesses of the molded base 22 and cover 24. The manual operatingmember includes an outwardly extending portion 116 for manually moving the circuit breaker between its manual OFF and manual ON positions in the manner fully set forth in aforementioned U.S. Patent No. 2,996,589.

Contact carrying arm 106 has'a braid member 120, secured thereto, with the opposite end of the braid memher being connected to braid lug 122. The electrical path then continues through bimetal 124, braid 126, conductor 128, to the electromagnetic coil 130. Electromagnetic coil is, in turn, electrically connected via conductor 131 to fuse receiving terminal clip 132. The circuit then continues through current limiting fuse device' 50, to the opposite fuse terminal clip 134, which is connected to externally accessible load terminal 110.

Thus, it should be recognized that device 20 includes a series circuit path from line terminal 100, via stationary and movable contacts 102, 104, bimetal 124, electromagnetic trip coil 130 and fuse 50, terminating at the load terminal 110.

The operating mechanism for bringing about the engagement and disengagement of cooperating contacts 102, 104 comprises a latchable cradle member 140, which is pivotally mounted at one end thereof, to base protrusion 142. Cradle also carries a kicker 145, which gives contact arm 106 a hammer-like blow during the tripping operation to insure separation of the circuit breaker contacts. 7

One end of an operating spring 148 is connected to cradle 140 at aperture 150, while the other end of operating spring 148 is connected to contact arm 106 at aperture 152. Operating spring 148 is always in tension, thereby urging contact arm end 115 upwardly into engagement with its pivotal mounting to manual operating member 114, and latchable cradle member 140 clockwise about its pivotal mounting 142. The force of operating spring 148 relative to the pivotal mounting of contact arm 106 also serves to urge the movable contact 104 into firm engagement with its cooperating stationary contact 102, as shown in FIG. 2.

Latchable cradle member 140 includes a latchable tip 144, which seats upon latch portion 154, carried by the lower end of the elongated bimetallic member 124. A hearing pin 156 is suitably secured to an intermediate region of elongated bimetallic member 124, as by welding, and enters suitable circular recesses of the circuit breaker base 22, and cover 24, for pivotally mounting the bimetallic element. The bimetallic element 124 is biased in a clockwise direction about its pivot 156 by spring 158. Calibrated adjustment of the trip unit is obtained by calibrating screw 160, which bears against intermediate connecting member 162. i Y

The electromagnetic actuation of the circuit breaker device is provided by coil 130, in conjunction with pole pieces 164, which upon actuation draws the armature member 166 towards the pole pieces. As the armature member 166 is drawn towards the pole pieces, its upper end 168 will strike the lower end of bimetallic member 124, thereby moving it in the direction shown by arrow 170. Further, the sustaining. of a moderate overload condition similarly deflects the elongated bimetallic element in the same direction of arrow 170. Such movement of the lower end of the bimetallic element 124 serves to effect releasing of the latched engagement between cradle tip 144 and latch member 154, so as to bring the circuit breaker mechanism to the overload tripped condition. An aperture 172 is provided for interpole tripping connection of the circuit breaker device, in a manner fully set forth in aforementioned U.S. Patent No. 2,996,589. As shown therein, the provision of the interpole trip arrangement permits a side-by-side stacked assembly of single pole units 20, appropriately coordinated for multi-pole operation, such that the actuation of one of the single pole units is transmitted to the adjacent units (by virtue of an interpole trip barnot shown) extending through aligned apertures 172 of the adjacently stacked units. Fuse 50 includes opposed end ferrule type terminals 184, 186, which when inserted in fuse compartment 182 are electrically connected to fuse clip terminals 132, 134 for completing the series circuit connection between the unitized device. Fuse 50 is retained within the novel fuse holder 190 of the instant invention, which includes a star-type resilient washer 192 for frictionally engaging the ferrule end terminal 184 of the fuse. The fuse holder 190 includes upper and lower protrusions 210 and 211 respectively. The insertion of fuse holder 190 within fuse compartment 182 requires that these protrusions 210 and 211 be in longitudinal alignment with the compartment openings 212, 213 along the top surface 30 of the access opening. That is, should an attempt be made to insert the fuse holder in any other orientation the protrusions 210, 211 will abuttingly engage either the top surface 30 of the device or the top surface of tulip type contact 132 to prevent insertion of the fuse. Thus, the insertion of the fuse requires that it be rotated 90 counter-clockwise from the position shown in FIG. 4.

Once the fuse holder 190 is inserted within compartment 182 and pressed downward, protrusion 210 will be disposed in arcuate guide slot 217 (see FIG. 14). Likewise, protrusion 211 will be disposed in arcuate guide slot 227 (see FIG. 15). The fuse holder may then be rotated clockwise 90 to the condition shown in FIGS. 2, 4, 14 and 15. This 90 clockwise movement is limited by the abutting engagement of protrusion 210 against wall 219 of guided slot 221; and protrusion 211 against wall 225 of guided slot 223. With the fuse holder turned fully clockwise to this condition, the engagement of protrusions 210 and 211 with-in the fuse compartment 182 prevents the outward movement of the fuse holder 190 and fuse 50. That is, the fuse holder must be turned counter-clockwise 90" from the condition shown in FIGS. 2, 4, 14 and 15, prior to fuse removal. This is quite important, in that it insures tripping of the circuit breaker prior to fuse removal, as will be now discussed. An interlock trip lever 194 is pivotally mounted at central aperture 252 to region 196 intermediate the circuit breaker compartment and current limiting fuse compartment. The interlock lever includes at one end a trip portion 201, which engages the lower end of bimetal 124 to effect coordinated tripping of the circuit breaker device upon fuse removal. The opposite end 254 of the interlock lever includes an inwardly extending rivet 202, which serves as a cam follower along circumferential cam surface 200, along the underside of fuse holder 190. That is, interlock lever 194 is biased counter-clockwise about its pivot by a spring member 198, which is seated at one end within extension 250 of the interlock lever. This counter-clockwise movement of the interlock lever urges end 201 into engagement with the free end of bimetal 124, to effect tripping of the circuit breaker. However, this counter-clockwise movement of interlock lever 194 is restrained by the abutting engagement of cam follower protrusion 202 at the opposite end of interlock lever, with the annular cam surface 200 provided along the bottom of rotatable fuse holder 190. With the fuse fully inserted as shown in FIG. 2, the interlock lever 194 is moved clockwise against the biasing action of spring 198 to its clockwise extreme, so as to prevent the engagement of end 201 with the elongated bimetal. Rotation of the fuse holder in the direction for removal of the fuse permits counter-clockwise movement of the interlock lever 194 about pivot 196, in the manner sequentially shown in FIGS. 6, 7 and 8. That is, as the cam follower 202 moves from the cam surface position 200-1 of FIG. 2 to the position 200-2 of FIG. 6, end 201 comes into engagement with the lower end of the bimetallic element 124. Further movement thereof to cam surface 200-3 (FIG. 7) causes sufficient counter-clockwise movement of interlock lever 194 and end 201 against the bimetal to defeat the latched engagement of cradle tip 144 with latch member 154. The circuit breaker mechanism will thus be in TRIP condition when the fuse holder is in a position to permit fuse removal, as shown in FIG. 8.

In order to provide proper safety, the cam surface 200 is interrelated in conjunction with the movement of interlock lever 194, such that tripping of the circuit breaker mechanism will occur upon the first forty-five degrees of counter-clockwise rotation of fuse holder 190 (FIG. 7), wherein of rotation is required to remove the fuse holder (FIG. 8). Thus, removal of the fuse will always be accompanied by tripping of the circuit breaker, and in multi-phase assemblies with the tripping of the associated phases. Conversely, the fuse 50 may only be inserted in device 20, when the circuit break portion thereof is in the contact disengaged condition.

It is, therefore, seen that my invention provides for the safe coordinated operation between a circuit breaker de vice and the insertion and removal of an associated current limiting fuse. That is, removal of the fuse provides automatic tripping of the circuit breaker, and the fuse may only be inserted with the circuit breaker contacts being in a disengaged position.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appending claims. More specifically, the utilization of the term compartment in the following claims is not limited to a completely closed compartment, as shown in the afore-described illustrative embodiment, but is intended to include the provision of separate sections for the circuit breaker and current limiting fuse.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows.

1. A circuit protective device, comprising a unitary housing including adjacent first and second compartments;

a dividing region for defining the boundary between said first and second compartments;

said first compartment containing a circuit breaker, in-

cluding a pair of cooperating contacts, a latchable operating means for moving said contacts between their engaged and disengaged conditions, and a trip means for automatically operating said latchable operating means to disengage said contacts when said device is subjected to predetermined overload conditions;

said second compartment including means for removably receiving a current limiting fuse;

circuit means extending between said compartments for electrically connecting said circuit breaker to said current limiting fuse; an interlock lever pivotally mounted at said dividing region;

said interlock lever including a first end extending into said first compartment and a second end extending into said second compartment; 7

biasing means for urging said first end in a first direction towards a first position, into tripping engagement with the latch of said operating means, to effect tripping of the circuit breaker;

said second compartment including interlock control means, responsive to fuse insertion;

said interlock control means movable to a first position,

when said fuse is fully inserted for urging said second in a second direction, in opposition to said bias ing means, for limiting the extent of pivotal movement of said first end towards said first position, and thereby restrain interlock tripping of said circuit breaker when said fuse is fully inserted;

said interlock control means movable to a second position, during fuse' removal, for permitting the movement of said first end to said first position, and provide interlock tripping of said circuit breaker.

2. A circuit protective device as set forth in claim 1: said second compartment including an elongated portion into which said fuse is longitudinally inserted; said fuse holder being rotatably inserted in said second compartment while said fuse is in said portion of said second compartment;

said fuse holder including protrusion means extending radially outward therefrom;

said second compartment including cooperating recess means adapted to receive said protrusion means for guiding fuse insertion and removal.

3. A circuit protective device as set forth in claim 2:

said protrusion means and cooperating recess .means requiring a predetermined relationship for fuse insertion and removal;

said predetermined relationship serving to place said interlock control means in said second position for insuring that fuse insertion or removal is automatically accompanied with tripping of the circuit breaker.

4. A circuit protective device, comprising a unitary housing including adjacent first and second compartments;

a dividing region for defining the boundary between said first and second compartments;

said first compartment containing a circuit breaker, in-

cluding a pair of cooperating contacts and a latchable operating means for moving said contacts between their engaged and disengaged conditions;

said second compartment including means for removably receiving a current limiting fuse;

circuit means extending between said compartments for electrically connecting said circuit breaker to said current limiting fuse;

an interlock lever pivotally mounted at said dividing region;

said interlock lever including a first end extending into said first compartment and a second end extending into said second compartment;

biasing means for urging said first end in a first direction towards a first position, into tripping engagement with the latch of said operating means, to effect tripping of the circuit breaker;

said second compartment including interlock control means, responsive to fuse insertion;

said interlock control means movable to a first position,

when said fuse is fully inserted for urging said second end in a second direction, in opposition to said biasing means, for limiting the extent of pivotal movement of said first end towards said first position, and thereby restrain interlock tripping of said circuit breaker when said fuse is fully inserted;

said interlock control means movable to a second position, during fuse removal, for permitting the movement of said first end to said first position, and provide interlock tripping of said circuit breaker;

a fuse holder for said current limiting fuse, insertable into said second compartment through an external access opening;

said interlock control means being a camming surface provided by said fuse holder;

said second end of the interlock lever including a cam follower in engagement with said camming surface.

5. A circuit protective device, as set forth in claim 4:

said fuse holder being rotatably inserted in said fuse compartment;

said camming surface being circumferentially disposed along the underside of said fuse holder.

6. A circuit protective device as set forth in claim 5:

said fuse holder including protrusion means outwardly extending therefrom;

said second compartment including cooperating recess 'said camming surface adapted to permit movement of said interlock lever to its interlock tripping position intermediate said first and second positions.

7. A circuit protective device, as set forth in claim 6:

said first and second positions being separated by said intermediate tripping position, during rotation between said first and second positions, being separated approximately 45 from said first position.

8. A circuit protective device as set forth in claim 6:

said protrusion means and cooperating recess means requiring a predetermined relationship at said second position for fuse insertion or removal;

said predetermined relationship serving to place said interlock control means in a tripping position for insuring that fuse insertion or removal is automatically accompanied with tripping of the circuit breaker.

9. A circuit protective device as set forth in claim 6:

said recess means being an annular guide slide for its cooperating protrusion means, of a circumferential extent corresponding to the rotational displacement between said first and second positions;

one end of said guide slot, corresponding to said second position, having a vertical passageway extending to said external access opening, the remaining circumferential portion of said guide slot being internal of said housing, and including an upper blocking wall intermediate the location of said guide slot and the external housing regions.

10. A circuit protective device as set forth in claim 9:

the circumferential extent of said guide slot being 90 and the other end of said guide slot abutting said protrusion means for limiting the rotational movement of said fuse holder between said first and second positions.

11. A multipole circuit protective arrangement, including a plurality of individual protective devices stacked side-by-side;

each of said devices being a self-supporting assembly contained within a unitary housing and forming a unitized assembly of a single pole circuit breaker and current limiting fuse;

interpole connecting means for maintaining the desired number of said unitized assemblies in stacked sideby-side arrangement for coordinated multipole operation;

said housing including adjacent first and second compartments;

said first compartment containing a circuit breaker, in-

cluding a pair of cooperating contacts, a latchable operating means for moving said contacts between their engaged and disengaged conditions, and a trip means for automatically operating said latchable operating means to disengage said contacts when said device is subjected to predetermined overload conditions;

said second compartment including means for removably receiving a current limiting fuse;

circuit means extending between said volumes for electrically connecting said circuit breaker to said current limiting fuse;

an interlock lever pivotally mounted at said dividing region;

said interlock lever including a first end extending into said first compartment and a second end extending into said second compartment;

biasing means for urging said first end in a first direction towards a first position, into tripping engagement with the latch of said operating means, to effect tripping of the circuit breaker;

said second compartment including interlock control means, responsive to fuse insertion;

said interlock control means movable to a first position, when said fuse is fully inserted for urging said second end in a second direction, in opposition to said biasing means, for limiting the extent of pivotal movement of said first end towards said first position, and thereby restrain interlock tripping of said circuit breaker when said fuse is fully inserted;

said interlock control means movable to a second position, during fuse removal, for permitting the movement of said first end to said first position, and provide interlock tripping of said circuit breaker;

a fuse holder for said current limiting fuse, insertable longitudinally into said second compartment through an external access opening.

12. A multipole circuit protective arrangement, as set forth in claim 11:

said interlock control means being a camming surface provided by said fuse holder;

said second end of the interlock lever including a cam follower in engagement With said camming surface.

13. A multipole circuit protective arrangement, as set forth in claim 11:

said fuse holder including first registry means, and an internal region of said second compartment including second registry means;

said first and second registry means adapted to engage and retain said current limiting fuse within said second compartment;

said registry means engaging upon rotation of said fuse holder in a first direction, and disengaging upon rotation in the opposed second direction;

such that said current limiting fuse is inserted in said second compartment by inward movement of said fuse holder into said access opening, and the rotation thereof in said first direction;

and said current limiting fuse is removed by rotation of said fuse holder in said second direction, and outward movement thereof out of said access opening.

References Cited UNITED STATES PATENTS 3,354,277 11/1967 Stanbach et al. 337-8 3,043,934 7/1962 Bodenschatz 337- 3,118,991 1/1964 Scott 337-150 BERNARD A. GILHEANY, Primary Examiner R. L. COHRS, Assistant Examiner US. Cl. X.R. 337-8, 35, 150

c-1s40(sc1s) g;;g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,474 373 Dated October 21, 1969 Inventor) Felix 1;. Myers It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 1 column 6 line 71 before "in a second" insert end Claim 11 column 8 line 64 the word "volumes" should read compartments SIGNED KND SEALED JUL 14970 Attest:

Edwurd M. Fletcher, Ir. mm L m Aneaing Officer Gomissioner o1 Patents 

